2 part dosing... Excessive.... or just me?

[Eric83]

I am dosing BRS 2 part, but the rates I'm dosing at seem rather high compared to what I can find referenced in videos/forums and I seem to get white calcium deposits on pumps and heaters, even tank walls rather quickly

I have a 75 gallon system with LPS only
1.025 salinity
8.05 pH
7.5 DKH
440 Ca
1420 Mg
0 NO3
0.06 PO4

I use a dosing pumps (calibrated) and have tested countless times (red sea/Hanna)to get the doses just right to keep dkh and ca stable. I am dosing 426ml of each part daily.

I get what I would consider to be excessive deposits on pumps and heaters - they need complete break down cleaning every 2 weeks (maybe this is normal but seems excessive to me).

Is this excessive dosing? I feel like it is. If so why would I be able to dose so much and my levels stay stable.

I have a couple hand fulls of marinepure cubes, it's about the only think I can think of to point to as a possible cause. They are suppose to have a ton of surface area, maybe the surfaces are calcifying? But I would think they would quickly clog and stop if that was the case.

 

[morpheas]

Have you considered that you might be deceived by a faulty test kit? The alk specifically. Have you measured with multiple kits? 426ml in a 75 gallon with lps only i think is a whole lot! And if you're seeing deposits it means that at 1420ppm magnesium 440 ca can be dissolved and Lord knows where the alk is. I would strongly suggest double and triple checking those readings you situation is definitely unusual in my book...

 

[melypr1985]

Agree^^ I'll bring in the #reefsquad for more eyes and ideas.

 

[Eric83]

I use a Hanna checker for alk. Have used a a few different bottles of reagent. Also have cross checked with a Red Sea kit and they agree.

 

[Downbeach]

Those parameter numbers, if accurate, are fine, so a second opinion would be a good idea. You're losing a lot of what you're dosing to abiotic precipitation, i.e. deposits on pumps and heaters, tank sides, etc. When my system was mostly LPS, I was able to keep my levels using ~ 2 gal of fully saturated kalk daily, so that would equal a dosing @ ~ 160mL of Randy's recipe #1(BRS's formula). Have you tried stopping the dosing for a day or two, to check the affect?

 

[Eric83]

Have not tried to outright stop dosing to see what happens.

Since Alk has been tested across multiple kits, pH tested via multiple calibrated probes....I might try to get a 2nd Ca test kit this afternoon just to confirm, or maybe have LFS test and verify the numbers I'm getting.

 

[BigJim]

Are you allowing some time between when you dose Alk and Ca? If you dose both at the same time, you will get precipitate. I allow ten minutes between when I dose Ca and when I dose Alk.

 

[Eric83]

Using Apex Dos dosing pumps, have the 2 part setup with slightly different (1-2ml) doses. This gets the doses running at different schedules so there is as little overlap in dosing times as possible. I've also tried locating the dosing lines in a couple different high flow areas.

 

[john.m.cole3]

there should be zero overlap in dosing times. the overlap is what's causing your chems to precipitate out. Try dosing calc on even hours and alk on the odd hours.

 

[Tori]

there should be zero overlap in dosing times. the overlap is what's causing your chems to precipitate out. Try dosing calc on even hours and alk on the odd hours.

I agree. From what I've read, I think you actually start pulling more cal and alk out of the water when they combine and precipitate. Could be why you have to dose so much to maintain your levels.

 

[Eric83]

Even if for example:

Alk doses 2.8ml every 10min
Ca doses 4.8ml every 17min

There would only be a very small overlap once every 170min, This is how apex is automatically breaking down the dose amounts/times

This would still cause a problem?

 

[morpheas]

Since you trust your numbers then I would agree that if it was me, my next step would have been to stop dosing all together for a few days and measure ca/alk daily and see what happens. Apparently you're precipitating what you're dosing (you see it on your equipment) so you need to figure out why. Do you trust your magnesium measurement? That's also very important in this phenomenon.

 

[BigJim]

Even if for example:

Alk doses 2.8ml every 10min
Ca doses 4.8ml every 17min

There would only be a very small overlap once every 170min, This is how apex is automatically breaking down the dose amounts/times

This would still cause a problem?

How long does the pump run when it is dosing those amounts? Even if the pumps aren't running at the same time, there may not be enough time in between for the alk to dissipate. I use a Bubble Magus doser and dose my alk at the top of the hour and my calcium ten minutes after the hour. I have never had to clean precipitate off any equipment in the two years I have been using this doser. You can check this theory by watching what happens when the calcium additive hits the water. If you are getting significant cloudiness, the alk isn't completely dissipated in your water.

 

[Eric83]

pump speed is 7ml/min. So a 2.8ml dose is about 24 seconds, and 4.8ml dose is about 41 seconds. The alk is just barely cloudy when hitting the water and is quickly dissipated. The Ca remains clear when entering the water.

 

[BigJim]

pump speed is 7ml/min. So a 2.8ml dose is about 24 seconds, and 4.8ml dose is about 41 seconds. The alk is just barely cloudy when hitting the water and is quickly dissipated. The Ca remains clear when entering the water.

I said that backwards, but you figured out what I was saying. I am out of ideas, but hopefully someone else will chime in.

 

[Eric83]

Ok, modified my dosers so:

Alk - Doses even hours 00:15-00:45 of the hour
Ca - Does odd hours 00:15-00:45 of the hour

This should be extra conservative with regards to the timing between each part. It allows for 30 minutes in between ALK/Ca

My only concern would be is pH swing, I currently get a swing of about 0.05 over 24hrs. Spacing the doses of ALK out further should create a larger swing, I just hope it's not too bad.

ALK at time of dosing timing update - 7.6dkh

 

[john.m.cole3]

a ph swing of .05 is rather small. It's not uncommon to see ph swing from 7.9 to 8.2 within a 24 hour period.

 

[Eric83]

Just got back from LFS

They did testing, but I don't feel too confident in the results... They used API and got
7.0dkh
340-360 Ca

I also bought salifert Mg and Ca test kits. I did a round of testing with old and new test kits and got:

DHK
hanna - 7.5
read sea - 7.1

Ca
Red Sea - 440
Salifert - 420

Mg
Red sea - 1460
salifert - 1380

So while all the numbers don't exactly match, I think they are close enough and within "normal" to rule out faulty test kits.

I'm thinking that completely stopping the dosing and monitor might be my only option. However I will probably wait until later tonight to stop, just on the outside chance that the dosing timing was the sole problem. At 426ml a day and with what should be a rather low consumption rate (LPS), I would expect to see a rather sharp spike that wouldn't take long to show it self if the problem has been corrected by rearranging the dosing schedule.

 

[john.m.cole3]

I agree that the problem will reveal itself if it was a timing of doses issue.

 

[BigJim]

The only other thing I can think of is to double check and make sure you are mixing the two part correctly. I don't see how that would explain the precipitate though.